Monitoring upstream machine wires and felts

ABSTRACT

Collecting data includes generating a sensor signal from each of a plurality of sensors located on a sensing roll, wherein each signal is generated when each sensor enters a region of a nip between the sensing roll and mating roll during each rotation of the sensing roll; wherein a web of material travels through the nip and a continuous band contacts a region of the web of material upstream from or at the nip. A periodically occurring starting reference is generated associated with each rotation of the continuous band and the signal generated by each sensor is received so that the one of the plurality of sensors which generated this signal is determined and one of a plurality of tracking segments associated with the continuous band is identified. The signal is stored to associate the respective sensor signal with the identified one tracking segment.

RELATED APPLICATIONS

The present application is related to U.S. patent application Ser. No.______ entitled MONITORING MACHINE WIRES AND FELTS (Attorney Docket No.TEC-064269) filed concurrently herewith, U.S. patent application Ser.No. ______ entitled COUNT-BASED MONITORING MACHINE WIRES AND FELTS(Attorney Docket No. TEC-064732) filed concurrently herewith, U.S.patent application Ser. No. ______ entitled MONITORING APPLICATOR RODS(Attorney Docket No. TEC-064888) filed concurrently herewith, U.S.patent application Ser. No. ______ entitled MONITORING APPLICATOR RODSAND APPLICATOR ROD NIPS (Attorney Docket No. TEC-064270) filedconcurrently herewith, and U.S. patent application Ser. No. ______entitled MONITORING OSCILLATING COMPONENTS (Attorney Docket No.TEC-064271) filed concurrently herewith, the disclosures of which areincorporated by reference herein in their entirety.

FIELD

The present invention relates generally to papermaking and, moreparticularly to monitoring one or more components in the papermakingprocess.

BACKGROUND

Nipped rolls are used in a vast number of continuous process industriesincluding, for example, papermaking, steel making, plastics calendaringand printing. In the process of papermaking, many stages are required totransform headbox stock into paper. The initial stage is the depositionof the headbox stock, commonly referred to as “white water,” onto apaper machine forming fabric, commonly referred to as a “wire.” Upondeposition, a portion of the white water flows through the intersticesof the forming fabric wire leaving a mixture of liquid and fiberthereon. This mixture, referred to in the industry as a “web,” can betreated by equipment which further reduce the amount of moisture contentof the finished product. The fabric wire continuously supports thefibrous web and transfers it to another fabric called a felt whichadvances it through the various dewatering equipment that effectivelyremoves the desired amount of liquid from the web. Water from the web ispressed into the wet felt and then can be removed as the wet felt passesa suction box. Dry felts can also be used to support the fibrous webthrough steam dryers.

One of the stages of dewatering is effected by passing the web through apair or more of rotating rolls which form a nip press or series thereof,during which liquid is expelled from the web via the pressure beingapplied by the rotating rolls. The rolls, in exerting force on the weband felt, will cause some liquid to be pressed from the fibrous web intothe felt. The web can then be advanced to other presses or dryingequipment which further reduce the amount of moisture in the web. The“nip region” is the contact region between two adjacent rolls throughwhich the paper web passes.

The condition of the various wires and felts can cause variations in theamount of liquid and other materials that are removed from the web whichcan, in turn, alter an amount of nip pressure applied to the web in anip region. Other components in the papermaking process such as sizeapplication stations, coating stations, doctor blades, and oscillatingshowers can also affect the characteristics of the web. Even nippressure axially along the roll and stable in time is beneficial inpapermaking and contributes to moisture content, caliper, sheet strengthand surface appearance. For example, a lack of uniformity in the nippressure can often result in paper of poor quality. Thus, there remainsa need to monitor various components of the papermaking process andaccount for their potential effect on nip pressure at one or more nipregions.

SUMMARY

One aspect of the present invention relates to a system associated witha sensing roll and a mating roll for collecting roll data. The sensingroll and mating roll are located relative to one another to create a niptherebetween, wherein a web of material travels through the nip from anupstream direction to a downstream direction and a continuous band,arranged to travel around in a loop pattern, contacts at least a regionof the web of material upstream from the nip. A plurality of sensors arelocated at axially spaced-apart locations of the sensing roll, whereineach sensor enters a region of the nip during each rotation of thesensing roll to generate a respective sensor signal. The system alsoincludes structure for generating a periodically occurring timereference associated with each rotation of the continuous band aroundthe loop pattern; and a processor to receive the periodically occurringtime reference and the respective sensor signal generated by eachsensor. The processor upon receiving the respective sensor signaloperates to: a) determine a particular one of the plurality of sensorswhich generated the respective sensor signal, b) based upon an amount oftime that elapsed between when the respective sensor signal wasgenerated and a most recent time reference, identify one of a pluralityof time-based tracking segments associated with the continuous band,wherein each of the plurality of tracking segments is, respectively,associated with a different amount of elapsed time, and c) store therespective sensor signal to associate the respective sensor signal withthe identified one time-based tracking segment.

In accordance with related aspects of the invention each of therespective sensor signals comprises a pressure value. In accordance withother aspects of the invention the continuous band comprises a pressfelt or a wire mesh. Also, in accordance with at least some aspects, thecontinuous band does not travel through the nip. Additionally, thestructure for generating a periodically occurring time referenceincludes a signal generator to generate a trigger signal on eachrotation of the continuous band as the reference location on thecontinuous band travels past a predetermined position.

In a related aspect of the present invention the processor receives therespective sensor signal for each of the plurality of sensors duringeach rotation of the sensing roll, and a plurality of the respectivesensor signals occur during a plurality of rotations of the sensingroll. For each one of the plurality of the respective sensor signals,the processor identifies an associated continuous band axial segment andits identified one time-based tracking segment.

In yet another related aspect, the continuous band comprises n axialsegments, having respective index values: 1, 2, . . . , n; thecontinuous band rotational period comprises m time-based trackingsegments, each having a respective, unique index value x in the rangeof: 1, 2, . . . , m, such that there are (n times m) unique permutationsthat are identifiable by a two-element set comprising a respective axialsegment index value and a respective time-based tracking segment indexvalue. A respective average pressure value can be associated with eachof the (n times m) unique permutations, each of the respective averagepressure values based on previously collected pressure readings relatedto the nip.

In another related aspect, each circumferential tracking segment of thecontinuous band contacts the web of material at an upstream locationfrom the region of the nip; and the index value q of eachcircumferential tracking segment is calculated based on a) a distancebetween the region of the nip and the upstream location and b) the indexvalue x of the corresponding time-based tracking segment. Furthermore,the index value x of a particular time-based tracking segment iscalculated independently from calculating the index value q of thecorresponding circumferential tracking segment.

In yet another related aspect of the invention, each circumferentialtracking segment of the continuous band contacts the web of material atan upstream location from the region of the nip; one particularcircumferential tracking segment contacts the web of material at theupstream location substantially concurrently with the signal generatorgenerating the trigger signal, and the index value q of eachcircumferential tracking segment is calculated based on a) a distancebetween the region of the nip and the upstream location, b) the indexvalue of the one particular circumferential tracking segment, and c) theindex value x of the corresponding time-based tracking segment.

Another aspect of the present invention relates to a method associatedwith a sensing roll and a mating roll for collecting roll data thatincludes generating a respective sensor signal from each of a pluralityof sensors located at axially spaced-apart locations of the sensingroll, wherein each respective sensor signal is generated when eachsensor enters a region of a nip between the sensing roll and the matingroll during each rotation of the sensing roll; the sensing roll andmating roll located relative to one another to create the niptherebetween, wherein a web of material travels through the nip from anupstream direction to a downstream direction and a continuous band,arranged to travel around in a loop pattern, contacts at least a regionof the web of material upstream from the nip. The method also includesgenerating a periodically occurring time reference associated with eachrotation of the continuous band around the loop pattern and receivingthe respective sensor signal generated by each sensor. Then, uponreceiving the respective sensor signal, a) determining a particular oneof the plurality of sensors which generated the respective sensorsignal, b) based upon an amount of time that elapsed between when therespective sensor signal was generated and a most recent time reference,identifying one of a plurality of time-based tracking segmentsassociated with the continuous band, wherein each of the plurality oftime-based tracking segments is, respectively, associated with adifferent amount of elapsed time, and c) storing the respective sensorsignal to associate the respective sensor signal with the identified onetime-based tracking segment.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the present invention, it is believed that thepresent invention will be better understood from the followingdescription in conjunction with the accompanying Drawing Figures, inwhich like reference numerals identify like elements.

FIG. 1 is an end, schematic view of a nip press, in accordance with theprinciples of the present invention, showing the formation of a webnipped between the nip rolls, the nip width of the nip press beingdesignated by the letters “NW.”

FIG. 2 is a side elevation view of a sensing roll showing the placementof a line of sensors in accordance with the principles of the presentinvention.

FIG. 3 illustrates how a rotation of the sensing roll and the matingroll can change a circumferential segment of the mating roll that entersa nip region coincidentally with a sensor on each rotation of thesensing roll, in accordance with the principles of the presentinvention.

FIGS. 4A and 4B illustrate a table of how collecting x sensor readingsfrom a sensor would be associated with the different circumferentialsegments of the mating roll, in accordance with the principles of thepresent invention.

FIG. 5 is a schematic drawing showing the basic architecture of aparticular monitoring system and paper processing line in accordancewith the principles of the present invention.

FIGS. 6, 7, and 8 depict matrices of different values that can becalculated for various axial segments and circumferential segments of amating roll in accordance with the principles of the present invention.

FIG. 9 illustrates an exemplary process configuration in accordance withthe principles of the present invention in which each of the variouscircles represents a rotating component (e.g. a roll) that help propelsa web of material 904 through the process.

FIG. 10 illustrates a detailed view of wet felt station in accordancewith the principles of the present invention.

FIG. 11 illustrates a flat portion of a felt loop in relation to asensing roll in accordance with the principles of the present invention.

FIGS. 12A-C illustrate a wet felt station with a pressing region havinga sensing roll that is downstream from a wet felt station that does nothave a press region with a sensing roll in accordance with theprinciples of the present invention.

FIGS. 12D, 12E and 12F illustrate detailed views of an alternative wetfelt station in accordance with the principles of the present invention.

FIG. 13 illustrates a sensing roll associated with the nip of a pressingregion of a felt station that is closest to and downstream from a wiremesh, in accordance with the principles of the present invention.

FIGS. 14A-14C illustrate a table of how collecting sensor readings froma sensor would be associated with the different tracking segments of afelt in accordance with the principles of the present invention.

FIGS. 15A-15C illustrate tables of how collecting sensor readings from asensor would be associated with the different tracking segments of adifferent felt in accordance with the principles of the presentinvention.

FIG. 16 illustrates different time-synchronized arrangements of the samesensor data readings in accordance with the principles of the presentinvention.

FIG. 17 is a flowchart of an exemplary method of time-synchronizing datain accordance with the principles of the present invention.

DETAILED DESCRIPTION

The present application is related to each of the following: U.S. patentapplication Ser. No. 14/268,672 entitled METHOD AND SYSTEM ASSOCIATEDWITH A SENSING ROLL AND A MATING ROLL FOR COLLECTING ROLL DATA, filedMay 2, 2014; U.S. patent application Ser. No. 14/268,706 entitled METHODAND SYSTEM ASSOCIATED WITH A SENSING ROLL AND A MATING ROLL FORCOLLECTING DATA INCLUDING FIRST AND SECOND SENSOR ARRAYS, filed May 2,2014; and U.S. patent application Ser. No. 14/268,737 entitled METHODAND SYSTEM ASSOCIATED WITH A SENSING ROLL INCLUDING PLURALITIES OFSENSORS AND A MATING ROLL FOR COLLECTING ROLL DATA, filed May 2, 2014,the disclosures of which are incorporated by reference herein in theirentirety.

In the following detailed description of the preferred embodiments,reference is made to the accompanying drawings that form a part hereof,and in which is shown by way of illustration, and not by way oflimitation, specific preferred embodiments in which the invention may bepracticed. It is to be understood that other embodiments may be utilizedand that changes may be made without departing from the spirit and scopeof the present invention.

As illustrated in FIG. 1, a sensing roll 10 and a mating roll 11 definea nip 12 receiving a fibrous web 16, such as a paper web, to applypressure to the web 16. It is contemplated that, in some cases, acontinuous band felt may support the web such that the felt and the webenter the nip 12. The sensing roll 10 comprises an inner base roll 20and an outer roll cover 22. As shown in FIG. 2, a set 24 of sensors 26is disposed at least partially in the roll cover 22. The set 24 ofsensors 26 may be disposed along a line that spirals around the entirelength of the roll 10 in a single revolution to define a helicalpattern, which is a common sensor geometry arrangement for roll covers.However, the helical pattern is merely an example and any arrangement iscontemplated in which at least one sensor is placed at each axialposition, anywhere along the circumference, at which data is to becollected. Each sensor 26 can, for example, measure the pressure that isbeing exerted on the sensor when it enters a region of the nip 12between the rolls 10 and 11. In particular, the set 24 of sensors 26 maybe positioned in the sensing roll 10, for example, at different axiallocations or segments along the sensing roll 10, wherein the axialsegments are preferably equally sized. In the illustrated embodiment,there are fourteen axial segments, labelled 1-14 in FIG. 2, each havingone sensor 26 located therein. It is also contemplated that the set 24of sensors 26 may be linearly arranged so as to define a line ofsensors, i.e., all sensors reside at the same circumferential location.One of ordinary skill will readily recognize that more than fourteen, orless than fourteen, axial segments may be provided as well along with acorresponding equal number of axially-spaced sensors located on thesensing roll. Also, in the description below, each sensor 26 may bereferred to as a pressure sensor, for example, but other types ofsensors are also contemplated such as, for example, temperature sensors.

Because having even nip pressure is beneficial during papermanufacturing, correctly calculating and displaying the nip pressureprofile are also beneficial since any corrections or adjustments to bemade to the rotating rolls based on an inaccurate calculated nippressure profile could certainly exacerbate any operational problems.There are three primary measurements of variability. The nip pressureprofile has variability that can be termed cross-directional variabilityas it is the variability of average pressure per cross-directionposition across the nip. Another type of variability represents thevariability of the high speed measurements at each position in thesingle line of sensors. This variability represents the variability ofother equipment in the paper making process such as, for example, wiresand felts and also including the rotational variability of the matingroll, i.e., the roll nipped to the sensing roll. The third variabilityin the nip profile includes the variability of multiple sensors,discussed below, at each cross-directional position of the roll. Thisvariability represents the “rotational variability” of the sensing rollas it rotates through its plurality of sensing positions and can only beseen by having a plurality of sensors in the same position.

One benefit of embedding a single set of sensors in covered rolls is tomeasure the real-time pressure profile and adjust loading pressures androll crowns or roll curvature (using, for example, internal hydrauliccylinders) to achieve a flat pressure profile. As an alternative to asingle set of sensors, two pluralities or arrays of sensors can beincluded on a sensing roll as described more fully in the earlierreferenced U.S. patent application Ser. No. 14/268,672 which isincorporated herein by reference in its entirety. The sensing roll can,for example, be separated into 14 axial segments. First and secondpluralities of sensors, respectfully, are disposed at least partially inthe roll cover. Each of the first plurality of sensors is located in oneof the 14 axial segments of the sensing roll. Likewise, each of thesecond plurality of sensors is located in one of the 14 axial segmentsof the sensing roll. Each sensor of the first plurality has acorresponding sensor from the second plurality located in a same axialsegment of the sensing roll. The first plurality of sensors can bedisposed along a line that spirals around the entire length of the rollin a single revolution to define a helical pattern. In a similar manner,the second plurality of sensors can be disposed along a line thatspirals around the entire length of the roll in a single revolution todefine a helical pattern. The first and second pluralities of sensorscan be separated from one another by 180 degrees. Each sensor measuresthe pressure that is being exerted on the sensor when it enters a regionof a nip. It is contemplated that the first and second pluralities ofsensors may be linearly arranged so as to define first and second linesof sensors, which are spaced approximately 180 degrees apart. Variousalternative configurations of a plurality of sensors are alsocontemplated. For example, a plurality of sensors could be helicallyarranged in a line that spirals, in two revolutions, around the entirelength of roll.

Typically, the sensing roll 10 and the mating roll 11 are sizeddifferently, i.e., they have a different size radially andcircumferentially. Each roll may have variations in its sizecircumferentially across the axial dimension. Further, as the rollrotates, the distance from the central axis (radial dimension) to theouter surface may vary for each axial position at the same angle ofrotation even were the circumferential dimensions to be the same foreach axial position.

For example, rolls are periodically ground which results is smallarbitrary changes in diameter from the manufacture's specification.There may also be slippage with one or more of the rolls resulting inthe sensing roll surface traveling at a speed that is different than themating roll surface. Consequently, it is rare that two rolls would haveexactly the same period of rotation or have periods that are exactharmonics.

Thus, as the sensing roll 10 and mating roll 11 travel through multiplerotations relative to one another, a particular sensor 26 may not alwaysenter the region of the nip 12 with the same circumferential portion ofthe mating roll 11 as it did in a previous rotation. This behavior canbe utilized to create data maps corresponding to the surface of themating roll 11. Different average pressure matrices, each collected andbuilt during different periods of time can be compared with one anotherto investigate how they vary from one another. Variability between thedifferent data maps can indicate possible problems with the mating roll11, such as roll surface irregularities, bearing wear, and roll flexing.Variability analysis of the sensor data may also indicate possibleproblems with upstream or downstream processing equipment, e.g.,upstream rolls, an upstream forming wire, an upstream felt or downstreamrolls.

The sensing and mating rolls 10 and 11 may be each separated into 14axial segments. All of the axial segments on the sensing roll 10 may ormay not be of the same length, and all of the axial segments on themating roll 11 also may or may not be of the same length. In theillustrated embodiment, it is presumed that all of the axial segments onthe sensing roll 10 are of the same length and all of the axial segmentson the mating roll 11 are of the same length. The axial segments on thesensing roll 10 may be aligned with the axial segments on the matingroll 11. Furthermore, the mating roll 11 may be separated intoindividual circumferential segments such as, for example, 22circumferential segments, all of substantially the same dimension.

FIG. 3 illustrates how rotation of the sensing roll 10 and the matingroll 11 can change a circumferential segment of the mating roll 11 thatenters a nip region coincidentally with a sensor on each rotation of thesensing roll 10. FIG. 3 is presented as series of position snapshotsfrom 1 to 23 of the rotating sensing roll 10 which also correspond to 22rotations of the sensing roll 10 and 23 rotations of the mating roll 11.The left-most portion of FIG. 3 shows a starting position (i.e., where afirst sensor reading is collected) and the right-most portion representsa position of the two rolls 10 and 11 after 22 rotations of the sensingroll 10 after the first sensor reading was collected. At the startingposition, circumferential segment #1 of the mating roll 11 is positionedin the region of the nip 12 along with the sensor 26A. The mating roll11, in this example, is rotating slightly faster than the sensing roll10 such that at a second position snapshot following a complete rotationfrom the starting position, the sensor 26A is once again positioned inthe region of the nip 12 but the mating roll 11 has rotated so thatcircumferential segment #2 is in the region of the nip 12. The values ofFIG. 3 are selected just as examples to illustrate with concrete numbersoperating principles of the present invention. In accordance with theexample values of FIG. 3, when the sensing roll had completed 22rotations, the mating roll 11 has completed 23 rotations. Thus, after 21rotations from the starting position (indicated by position #22 in FIG.3), the sensor 26A of the sensing roll 10 has been able to collect 22sensor readings, presuming it collected a reading at the startingposition, and has “seen” all portions of the circumference of the matingroll 11. Therefore, 22 circumferential segments can be selected as anexample number of circumferential segments. One of ordinary skill willrecognize that the mating roll 11 could be broken into morecircumferential segments but that it would take more than 22 rotationsof the sensing roll 10 to collect data from sensor 26A that correspondsto each of the different circumferential segments.

It would be rare that the period of the mating roll would be an integerratio of the period of the sensing roll. Hence it is very unlikely thata stationary pattern would be maintained between these rolls and thiswould tend to even out the sampling of tracking segments, discussedbelow.

Because the one sensor 26A enters the region of the nip 12 concurrentlywith different circumferential segments of the mating roll 11 in theillustrated embodiment, the nip pressure measured by the one sensor 26Amay vary during sequential roll rotations due to the change in pressurecaused by the mating roll 11. Aspects of the present inventioncontemplates mapping readings, or signals, from each sensor 26 of theset 24 over time to see how the pressure readings, or signals, vary foreach sensor due to each sensor entering the region of the nip 12concurrently with different circumferential segments of the mating roll11. As noted above, the mapped data may be used to determine possibleproblems with the mating roll 11 and, as more fully described below,data collection can be performed involving possible problems related toupstream or downstream processing equipment other than the sensing roll10 and the mating roll 11.

Hence, the present invention contemplates using sensors 26 to measurefor rotational variability that is generated by the high speed rotationof the mating roll 11 when pressure signals, or readings, from thesensors 26 are time synchronized to the mating roll position. In orderto measure for rotational variability, the mating roll 11 must have someimpact on the pressure in the nip 12 to be measured. The dominant impacton the sensed nip pressure will likely be that of the mating roll 11which directly presses against the sensing roll 10. However, it may bepossible to synchronize sensor measurements with upstream rolls (notshown) which form another nip and impact the water content and thicknessof the web which affect the nip pressure seen by the sensing roll 10.Furthermore, as rolls (not shown) in a downstream nip may pull the weband cause changes in web tension, it may be possible to also synchronizesensor measurements with these rolls. The sensing and mating rolls 10and 11 will be used to illustrate the principles of this invention;however all principles are applicable to upstream and downstreamprocessing equipment, such as upstream and downstream rolls, an upstreamforming wire or an upstream felt.

Continuing the example of FIG. 3, the mating roll 11 may have rotationalcharacteristics that generate, for example, a sinusoidal pressurepattern which is 8 pounds per square inch (psi) peak-to-peak. In theillustrated example of FIGS. 4A and 4B, to start, the pressure patternis “0” when circumferential segment #1 of the mating roll 11 is in theregion of the nip 12. FIGS. 4A and 4B are a table of how collecting 51sensor readings from sensor 26A would be associated with the differentcircumferential segments of the mating roll 11. The left column 402 isthe sequential number assigned to the sensor reading and the middlecolumn 404 represents a pressure reading value from sensor 26A accordingto the sinusoidal pattern described above and right column 406 is thecircumferential segment of the mating roll 11 in the region of the nipwhen a corresponding pressuring reading is taken from the sensor 26A.Each pressure reading value is time-synchronized with the period ofrotation of the mating roll 11 by associating that value with one of thecircumferential segments of the mating roll 11 that was in the region ofthe nip 12 when the pressure reading was sensed.

One convenient way to characterize the difference in periodicity isusing units-of-measure that measure that difference in terms of timesegments, e.g., 22 time segments in the illustrated embodiment. Thelength of each time segment is the mating roll period divided by thenumber of predefined time segments. As discussed below, the predefinednumber of time segments may correspond to a predefined number of matingroll circumferential segments. A period of the sensing roll 10 can bedescribed as being x time segments smaller/larger than a period of themating roll 11. For example, according to FIG. 3, the sensing roll 10may have a period that is 1.0 mating roll time segment more than theperiod of the mating roll 11 (equivalently, the mating roll 11 can havea period that is 1.0 mating roll time segment smaller than the period ofthe sensing roll). In such an example, as the sensing roll 10 makes onecomplete revolution, the mating roll 11 will make more than a completerevolution by an amount equal to 1.0 mating roll time segment due to ithaving a smaller period than the sensing roll 10.

As noted above, the 22 time segments of the mating roll period cancorrespond to 22 circumferential segments around the mating roll 11.Thus, even though, at a conceptual level, it is the period of the matingroll 11 that is being separated into a plurality of time segments, thatconcept can correspond to a physical circumference of the mating roll11, wherein each individual time segment of the mating roll period alsocorresponds to a circumferential segment around the mating roll 11.Accordingly, differences in rotational periods between the sensing roll10 and the mating roll 11 measured in units of “time segments” can justas easily be considered in units of “circumferential segments.” In thedescription of at least some embodiments of the present invention below,reference to “circumferential segments” is provided as an aid inunderstanding aspects of an example embodiment of the present invention.However, one of ordinary skill will recognize that “time segments” andmating roll periodicity could be utilized as well without departing fromthe scope of the present invention. The “circumferential segments” and“time segments” can also be referred to generically as “trackingsegments”; this latter term encompassing both types of segmentsassociated with the mating roll 11 and other periodic components asdescribed below.

As mentioned above, data similar to that of FIGS. 4A and 4B is capturedfor each sensor 26 of the set 24. Thus, as each sensor 26 arrives at theregion of the nip 12 and senses a pressure reading, a particular matingroll outer surface portion at an axial location corresponding to thatsensor and at one of the 22 circumferential segments of the mating roll11 will also be in the nip 12. Determining the mating roll segment thatis in the nip 12 can be accomplished in a variety of different ways. Oneway involves indexing a particular one of the 22 mating roll segmentswith a trigger signal that is fired each time the mating roll 11completes one revolution; a time period since the last trigger signalcan be used to determine which of the 22 segments (measured relative tothe indexed segment) is in the nip 12. For example, if the time betweeneach firing of the trigger signal is 220 ms, then each time segment is10.0 ms, which corresponds to one of the 22 mating roll circumferentialsegments. A pressure signal generated by a sensor 26 in the nip regionoccurring at 30 ms after the trigger signal would be assigned to timesegment 3 as three 10.0 ms segments will have passed, e.g., the nipregion, from when the trigger signal is made to when the pressure signalis generated.

In FIG. 5, a processor 903 can be present that can generate a real-timenip profile. In addition, the processor 903 can also receive a triggersignal 901 related to the rotation of the mating roll 11. As justdescribed, some circumferential segment or position 907 of the matingroll 11 can be indexed or encoded such that a signal generator 900detects the encoded segment 907 and generates the trigger signal 901each time the signal generator 900 determines that the segment 907 ofthe mating roll 11 completes another full rotation. When the mating roll11 is rotated such that the circumferential position or segment 907 isaligned with a detector portion of the signal generator 900, then theone of the 22 circumferential segments that happens to be positioned inthe nip region can arbitrarily be labeled as the first circumferentialsegment such that the other circumferential segments can be numberedrelative to this first segment. This particular rotational position ofthe mating roll 11 can be considered a reference position. As the matingroll 11 rotates, its rotational position will vary relative to thatreference position and the amount of this variance determines which ofthe 22 circumferential segments will be positioned in the nip region.Accordingly, based on the rotational position of the mating roll 11relative to that reference position a determination can be made as towhich of the 22 circumferential segments is in the nip region when aparticular sensor 26 generates a pressure signal. FIG. 5 illustrates theoverall architecture of one particular system for monitoring paperproduction product quality. The system of FIG. 5 includes the processor903, noted above, which defines a measurement and control system thatevaluates and analyzes operation of the roll 11. The processor 903comprises any device which receives input data, processes that datathrough computer instructions, and generates output data. Such aprocessor can be a hand-held device, laptop or notebook computer,desktop computer, microcomputer, digital signal processor (DSP),mainframe, server, other programmable computer devices, or anycombination thereof. The processor 903 may also be implemented usingprogrammable logic devices such as field programmable gate arrays(FPGAs) or, alternatively, realized as application specific integratedcircuits (ASICs) or similar devices. The processor 903 may calculate anddisplay the real-time average pressure profile calculated at the end ofthe prior collection session. For example, the pressure measurementsfrom the sensors 26 can be sent to a wireless receiver 905 fromtransmitter(s) 40 located on the sensing roll 10. The signals can thenbe communicated to the processor 903. It is contemplated that theprocessor 903, in addition to calculating a real-time average pressureprofile, may use the real-time average pressure profile to automaticallyadjust crown and loading mechanisms to achieve a flat pressure profile.Crown and loading mechanisms may also be adjusted manually by anoperator using information provided by the real-time average pressureprofile.

There are other ways to determine the position of the mating roll 11.One way is to use a high precision tachometer that divides the rotationof the roll 11 into a number of divisions, perhaps 440. In this example,each time segment would be 20 positions on the high precisiontachometer. All methods of determining the position of the mating rollare included in this invention.

In an example environment in which there are 14 axially arranged sensors26, each of which can be uniquely referred to using an axial segmentindex value that ranges from “1” to “14”, and there are 22circumferential segments on the mating roll 11 (or time segments), eachof which can be uniquely referred to using a tracking segment indexvalue ranging from “1” to “22”, there are 308 (i.e., 22×14=308) uniquepermutations of pairs consisting of a sensor number and acircumferential segment number (or time segment number), wherein eachpermutation is identifiable by a two-element set comprising a respectiveaxial segment index value and a respective tracking segment index value.In the illustrated embodiment, the sensor numbers also correspond to themating roll axial segments. Therefore the data collected can beconsidered a 22×14 matrix as depicted in FIG. 6. Each row of FIG. 6represents one of the 22 mating roll circumferential segments (or timesegments) and each column represents one of the 14 axially arrangedsensors 26 and, thus, each cell represents one of the possible 308permutations. Each column also corresponds to a mating roll outersurface portion at an axial location aligned with and corresponding tothe sensor 26 assigned that column. Each cell represents a combinationof a sensor number (or axial segment number) and a particular matingroll circumferential segment (or time segment). For example, cell 100represents a value that will relate to a pressure reading that occurredwhen sensor number 14 (number 14 of the 1-14 sensors defining the set24) entered the region of the nip 12 concurrently with a mating rollouter surface portion at an axial location corresponding to sensornumber 14 and mating roll circumferential segment number 1 (or timesegment number 1). Thus, each cell of the matrix represents a uniquepermutation from among all the possible permutations of different axialsegment numbers (e.g., 1-14) and circumferential segment numbers (e.g.,1-22) (or time segments 1-22). A value stored in a particular matrixelement is thereby associated with one particular permutation ofpossible axial segment numbers and circumferential segment numbers (ortime segments).

The matrix of FIG. 6 can, for example, be a “counts” matrix wherein eachcell represents the number of times a particular sensor and a particularmating roll outer surface portion at an axial location corresponding tothat sensor and a particular mating roll circumferential segment wereconcurrently in the region of the nip 12 to acquire a pressure readingvalue. FIG. 7 illustrates a similarly sized matrix (i.e., 22×14) but thevalues within the matrix cells are different from those of FIG. 6. Thecell 200 still represents a value that is related to sensor number 14(or axial segment 14, out of 1-14 axial segments, of the mating roll 11)and circumferential segment 1 but, in this example, the value is acumulative total of pressure readings, e.g., in pounds/inch, acquired bythe sensor for that circumferential segment during a plurality ofrotations of the sensing roll 10. Thus, each time sensor number 14happens to enter the region of the nip 12 along with the mating rollcircumferential segment number 1, the acquired pressure reading value issummed with the contents already in the cell 200. Each of the 308 cellsin this matrix of FIG. 7 is calculated in an analogous manner for theirrespective, associated sensors and segments.

From the matrices of FIG. 6 and FIG. 7, an average pressure matrixdepicted in FIG. 8 can be calculated. For example, cell 100 includes thenumber of pressure readings associated with sensor number 14 (or axialsegment 14 of the mating roll 11) and circumferential segment number 1while cell 200 includes the total or summation of all those pressurereadings. Thus, dividing cell 200 by cell 100 provides an averagepressure value for that particular permutation of sensor number andmating roll circumferential segment number which entered the region ofthe nip 12 concurrently.

As a result, the matrix of FIG. 8 represents an average pressure valuethat is sensed for each particular sensor number and mating rollcircumferential segment number. The length of time such data iscollected determines how many different pressure readings are used insuch calculations.

The raw pressure readings, or pressure signals, from the sensors 26 canbe affected by a variety of components in the system that move the webof material. In particular, the average values in the average pressurematrix of FIG. 8 are related to variability synchronized to the matingroll 11. However, there may be other variability components that are notsynchronized with the mating roll 11 such as variability in a crossdirection (CD), shown in FIG. 2. One measure of this CD variability iscaptured by calculating an average for each column of the averagepressure matrix. Thus, the average pressure matrix of FIG. 8 can alsoinclude a row 302 that represents a column average value. Each of the 14columns may have 22 cells that can be averaged together to calculate anaverage value for that column. For example, cell 304 would be theaverage value in the 22 cells of the second column of the averagepressure matrix.

Individual collection sessions of pressure readings to fill the matricesof FIGS. 6, 7, and 8 may be too short to build robust and completematrices due to data buffer and battery life limitations of dataacquisition systems in communication with the sensing roll 10. In suchcases, consecutive collection sessions can be combined by not zeroingthe matrices (i.e., counts and summation matrices) upon starting a newcollection session or combining the separate matrices collected in apost hoc fashion. Consequently, collections may be stopped and restartedwithout loss of data fidelity as long as the synchronization of themating roll is maintained. In particular, combining multiple collectionsessions that are separated by gaps in time can be beneficial to helppopulate the matrices. For example, if the period difference between thetwo rolls were closer to 2.001 instead of 1.0 time or circumferentialsegments, the collection would have a tendency to collect only evenlynumbered time/circumferential segments in the short term (i.e., evenlynumbered segments are those that are offset an even number of segmentsfrom a starting segment) until sufficient time has passed to move thecollection into the odd numbered time/circumferential segments.Combining collection sessions separated by a long time delay may help toshift the collection so that data is more uniformly captured for all thedifferent time/circumferential segments because there is no expectationthat the period of the mating roll will be related to arbitrary timegaps between collection sessions.

The press of FIG. 1 can be located at a number of different positionswithin the chain or serial sequence of different components that arepart of a modern paper processing operation. FIG. 9 illustrates anexemplary process and system configuration in accordance with theprinciples of the present invention in which each of the various circlesrepresents a rotating component (e.g. a roll) that helps propel a web ofmaterial 904 through the process/system. The process starts at a headbox902 where a fiber slurry is distributed over a wire mesh 906 whichallows liquid to readily drain from the slurry. From the wire mesh 906,the web of material 904 travels to a first wet felt station 908 thathelps dry the web of material 904. A felt 909 at the first station 908is a continuous band arranged to travel in a loop pattern around aplurality of rolls 940. In the example of FIG. 9, there are four rolls940. The felt 909 enters a press area 916 between one of the rolls 940and a sensing roll 918 with the web of material 904. The sensing roll918 may operate similar to the sensing roll 10 of FIG. 1. Downstreamfrom the wet felt station 908 is another wet felt station 910 having itsown felt 911 traveling in a loop pattern around another set of fourrolls 941. There is also a second press region 920 having a press roll922, which, in the illustrated embodiment, is not a sensing roll. Thelast wet felt station 912 has a felt 913 traveling in a loop patternaround another set of four rolls 942. The felt 913 together with the webof material 904 is pressed by one of the rolls 942 and a second sensingroll 926 in a third press region 924. The felts 909, 911, 913 arepressed into the web of material in their respective press regions 916,920, 924 to absorb liquid from the web of material 904. In this manner,the web of material 904 is drier after passing through the wet feltstations 908, 910, 912. By “drier” it is meant that the fibers in theweb of material 904 have a higher percentage by weight of fibers afterthe wet felt stations than before. Additional drying can be performed,however, by separate dryers 914 before the web of material 904progresses further downstream in the process of FIG. 9. The variousfelts and rolls of FIG. 9, and the spacing between the differentstations are not shown to scale but are provided to simplify descriptionof various aspects of different embodiments of the present invention.For example, the web of material 904 does not travel unsupported forlong distances. Typically, the web of material 904 will be removed fromone felt and be picked up by a next-downstream felt. In additional, theweb of material can be supported by other supporting rolls and bytension between various rolls.

A felt (e.g., 909) can have variations in its material that causedifferent effects on the web of material 904. For example, seams, wornspots, or even holes, may not be as effective at removing liquid fromthe web of material 904 as portions of the felt 909 that are in goodcondition. Thus, some regions of the web of material 904 may have moreor less water relative to other regions of the web of material 904 dueto variations in the felt 909, i.e., a worn portion of the felt 909 maynot remove as much moisture from a region of the web of material that itengages as compared to a portion of the felt that is in good conditionand engages another region of the web material. When a wetter region ofthe web of material travels through a nip in one of the press regions(e.g. 916), a pressure sensed by a sensor on a sensing roll (e.g., 918)may be greater than when a drier region of the web material 904 passesthrough the nip. Also, the felts 909, 911, 913 may be porous inconstruction and, thus, some portions of a felt may become clogged withdebris, fibers, or other contaminants. When a clogged portion of a feltis pressed into, or otherwise interacts with, and affects a region ofthe web of material 904, not as much moisture will be removed from thatregion of the web of material as compared with other regions of the webof material 904 that were pressed into portions of the felt that werenot clogged, or not as clogged. When that region of the web of materialthat did not have as much moisture removed travels through a nip in oneof the press regions (e.g. 916), a pressure sensed by a sensor on asensing roll (e.g., 918) may be greater than when the other regions thatexperienced more moisture being removed pass through the nip. Further,when a clogged portion of a felt travels through the nip in one of thepress regions (e.g., 916), a pressure sensed by a sensor on a sensingroll (e.g., 918) may be greater than when a non-clogged portion of thefelt passes through the nip. Thus, a pressure reading sensed in a nipcan reveal effects that a felt had on the web of material 904 upstreamof that nip in addition to revealing effects from a felt passing throughthe nip.

FIG. 10 illustrates a detailed view of the wet felt station 912illustrated in FIG. 9 in accordance with the principles of the presentinvention. The felt 913 extends in a cross-machine direction into theplane of the drawing sheet and, as described earlier, the felt 913 is acontinuous band arranged to travel around in a loop pattern around thefour rolls 942 in a direction shown by arrow 1001. Accordingly, the felt913 has a regular period of rotation around this loop pattern. Thus,different portions of the felt 913 each periodically travel through aregion of the nip 1201 along with the web of material 904. The region ofthe nip 1201 is formed between the sensing roll 926 and a mating roll942A similar to the arrangement described earlier with respect to FIGS.1-3.

The felt 913 may be separated into a predefined number of axialsegments, such as 14 in the illustrated embodiment, such that the 14axial segments of the felt 913 are axially aligned with 14 axiallyspaced apart sensors 26 provided on the sensing roll 926.

The felt station 912 can have a period of rotation that can be dividedinto different tracking segments in the same manner as the period ofrotation of the mating roll 11 was divided into 22 tracking segments asdescribed earlier. Thus, the tracking segments related to the felt 913can either be a plurality of time segments of the period of rotation ofthe continuous felt band 913 around the loop pattern or a plurality ofphysical circumferential segments on the continuous felt band 913. Thesegments of the felt, only segments 1004A, 1004B, 1004C, 1004AA aredesignated in FIG. 10 with the remaining segments not being specificallyidentified, may, for example, be separate circumferential segments witheach having an index relative to a fixed reference position 1006 on thefelt 913.

As an example, the reference position 1006 can make 1 complete rotationaround the loop pattern in the same amount of time that the sensing rollmakes 31 rotations. Accordingly, the felt 913 can be segmented into 31different physical circumferential segments 1004A-1004AE or,equivalently, the period of rotation of the felt 913 around its loop canbe segmented into 31 time-based segments. In other words, because therespective portions of the felt 913 and the sensing roll 926 at a regionof the nip 1201 are travelling at substantially the same linear speedthe circumference of the loop of felt 913 will, for this example, beabout 31 times greater than the circumference of the sensing roll 926.In the drawings, as mentioned earlier, various rolls, loops of felt, andwire meshes are not drawn to scale but, instead, are presented so as notto obscure aspects of the present invention.

Using the same principles as used when describing the mating roll 11 ofFIG. 3, the felt 913 can be segmented into 31 tracking segments, forexample. As an example and as will be discussed further below, there canbe a portion 1002 of the felt 913 located at a circumferential segment1004AA of the felt 913 that defines tracking segment #27 and at an axiallocation aligned with a pressure sensor 26A (one of 14 pressure sensorson the sensing roll 926 in the illustrated embodiment) on the sensingroll 926 that causes an increase in pressure in the region of the nip1201 of approximately 4 psi as compared to a pressure increase of about0 psi for all other portions of the felt 913 at different axial andcircumferential locations. In a manner similar to how data in FIGS. 4Aand 4B was collected in a manner time-synchronized with the rotationalperiod of the mating roll 11, sensor readings from the region of the nip1201 defined by the sensing roll 926 and the mating roll 942A can alsobe collected in a manner time-synchronized with the period of rotationof the felt 913.

In FIG. 10, a processor 903 can be present that can receive a triggersignal related to the rotation of the felt 913. Some circumferentialsegment or position 1006 of the felt 913 can be indexed or encoded suchthat a signal generator 900A detects the encoded segment 1006 andgenerates a trigger signal each time the signal generator 900Adetermines that the segment 1006 of the felt 913 completes another fullrotation. When the felt 913 is rotated such that the circumferentialposition or segment 1006 is aligned with a detector portion of thesignal generator 900A, then the one of the 31 circumferential segmentsthat happens to be positioned in the nip region can arbitrarily belabeled as the first circumferential segment such that the othercircumferential segments can be numbered relative to this first segment.This particular rotational position of the felt 913 can be considered areference position. As the felt 913 rotates, its rotational positionwill vary relative to that reference position and the amount of thisvariance determines which of the 31 circumferential segments will bepositioned in a region of the nip 1201. Accordingly, based on therotational position of the felt 913 relative to that reference positiona determination can be made as to which of the 31 circumferentialsegments is in the nip region when a particular sensor 26A generates apressure signal.

FIGS. 14A-14C is a table of how collecting 86 sensor readings fromsensor 26A (one of 14 pressure sensors on the sensing roll 926 in theillustrated embodiment) would be associated with the different trackingsegments (e.g., 31 tracking segments in the illustrated embodiment withonly segments 1004A, 1004B, 1004C and 1004AA being designated in FIG.10) of the felt 913. The data in FIGS. 4A and 4B and 14A-14C issimulated data and, as noted before, could be generated by rolls andfelts having different relative sizes as compared to those depicted inthe figures. As a simulation, the data is nicely behaved and thetracking segments advance one segment per sensing roll rotation. Actualdata may not be this well behaved as there may be no relation to thetracking segment length and sensing roll rotation period. Actualcollections therefore are like to have skips (consecutive readings innon-consecutive tracking segments) and repeats (consecutive readings inthe same tracking segment). The result of this is that the trackingsegments are not evenly sampled. However, as discussed in more detail inU.S. patent application Ser. No. 14/268,672 entitled METHOD AND SYSTEMASSOCIATED WITH A SENSING ROLL AND A MATING ROLL FOR COLLECTING ROLLDATA, filed May 2, 2014, which was incorporated by reference above, ifdata is collected for a sufficient amount of time, it is unlikely thatany tracking segments will not have corresponding sensed data even ifthere is unevenness in the data sampling per tracking segment. Similarto FIGS. 4A and 4B, the left column 402A is the sequential numberassigned to the sensor reading and the next column 404A represents a rawnip pressure reading value when the pressure sensor 26A enters theregion of the nip 1201 defined by the sensing roll 926 and the matingroll 942A. As discussed above, each pressure reading value in column404A can be time-synchronized with the period of rotation of the matingroll 942A by associating that value with one of the 22 circumferentialsegments, see column 406A, of the mating roll 942A that was in theregion of the nip 1201 when the pressure reading was sensed. Inaddition, each pressure reading value in column 404A can also betime-synchronized with the period of rotation of the felt 913 byassociating that value with one of the 31 tracking segments, in column1402, of the felt 913 that was in the region of the nip 1201 when thepressure reading was sensed.

Similar to the mating roll 11 being segmented into axial segmentscorresponding to the different locations of the sensors 26 on thesensing roll 10, the felt 913 can be segmented into cross-machinedirection (or axial) segments as well, as noted above. FIG. 11illustrates a felt 913 in relation to a sensing roll 926 in accordancewith the principles of the present invention. In particular, the view ofFIG. 11 is from the perspective of being below the sensing roll 926 andlooking upwards towards the felt 913. The felt 913 has a width W2 thatis substantially similar to a width W1 of the web of material 904 thatare both typically smaller than the length L of the sensing roll 926.Thus, either or both of the web of material 904 and the felt 913 can bebroken into multiple axial segments 1102 that each correspond to one ofthe sensor locations on the sensing roll 926, e.g., 14 axial segments inthe illustrated embodiment. Accordingly, similar matrices of “counts”,“sums” and “averages” as described in FIGS. 6-8 can be constructed forthe data from FIGS. 14A-14C but arranged in a manner time-synchronizedwith the period of the felt 913. In the example provided above, eachsuch matrix would have (31×14), or 434, cells.

In the example stations of FIG. 9 and as noted above, not every wet feltstation 908, 910, 912 necessarily has a press region 916, 920, 924 thatincludes a sensing roll. FIG. 12A illustrates the wet felt station 912with the press region 924 having the sensing roll 926 that is downstreamfrom the wet felt station 910 that does not have a press region with asensing roll in accordance with the principles of the present invention.

In FIG. 12A, the sensing roll 926 is associated with the region of thenip 1201 of the press region 924 while the press region 920 of the wetfelt station 910 may not necessarily include a sensing roll. However,the felt 911 of the wet felt station 910 still rotates as a continuousband in a loop pattern similar to the manner described with respect tothe felt 913 of FIG. 10. Accordingly, the felt 911 has a regular periodof rotation around this loop pattern. Thus, different portions of thefelt 911 each periodically contact a region of the web of material 904upstream from the region of the nip 1201 even though the felt 911 itselfdoes not travel through the region of the nip 1201.

In FIG. 12A, a portion 1207 of the felt 911 (having corresponding axialand circumferential locations on the felt 911) is shown that contactsthe web of material 904 in a periodic manner as the web of material 904passes through the region of the nip 1203 of the press region 920.Regions 1206, 1208, 1210 and 1214 (each having corresponding axial andcircumferential positions on the web of material 904), evenly spaced bya distance d in the circumferential direction, of the web of material904 that were in the region of the nip 1203 concurrently with theportion 1207 of the felt 911 are shown in FIG. 12A, i.e., in theillustrated embodiment the felt portion 1207 engages each of the web ofmaterial regions 1206, 1208, 1210 and 1214 at different occurrences ortimes when in the nip 1203. When those web of material regions 1206,1208, 1210 and 1214 travel through the region of the nip 1201 of thedownstream felt station 912, the pressure readings from the sensing roll926 in the downstream felt station 912 can be affected by the impactthat the felt portion 1207 had on the web of material regions 1206,1208, 1210 and 1214 that it contacted in the upstream nip 1203. Asexplained earlier, the condition of the felt 911 as it is pressed intothe web of material 904 can affect, for example, the amount of moisturethat is drawn out from the contacted region of the web of material 904or other characteristics of the web of material 904. Thus, some regionsof the web of material 904 may be wetter or drier relative to oneanother and cause higher or lower pressure readings when passing throughthe region of the nip 1201.

The felt station 910 can have a period of rotation that can be dividedinto different time-based tracking segments of the period of rotation ofthe continuous band around the loop pattern of the four rolls 941. Also,the felt 911 can be divided into a plurality of physical circumferentialtracking segments on the continuous band. In the illustrated embodiment,the felt 911 comprises 37 physical circumferential segments, with onlyfour segments 1202A, 1202B, 1202C, 1202G being designated in FIG. 12A.The 37 physical segments, may, for example, be separate circumferentialsegments with each having an index relative to a fixed referenceposition 1205 on the felt 911. As discussed below, a particulartime-based tracking segment, e.g., #5, may not correspond to a physicalcircumferential segment having that same index value.

Returning to FIGS. 14A-14C, each of the simulated raw pressure readingsfrom the region of the nip 1201 that are shown in column 404A can beassociated with a specific single time-based tracking segment of theperiod of rotation of the felt 911. These time-based tracking segmentscan then be correlated to a specific physical circumferential segment ofthe felt 911 as well. Thus, the table of FIGS. 14A-14C also shows howcollecting 86 sensor readings from the sensor 26A (one of 14 pressuresensors on the sensing roll 926) would be associated with differenttime-based tracking segments, shown in column 1404 which, in turn, canbe correlated to the different physical circumferential trackingsegments (e.g., 37 physical tracking segments with only 1202A, 1202B,1202C, 1202G being designated in FIG. 12A) of the felt 911. As describedearlier, the left column 402A is the sequential number assigned to thesensor reading and the next column 404A represents a simulated rawpressure reading sensed at the region of the nip 1201 by the sensor 26Aon the sensing roll 926. Each such pressure reading will have a valuethat is related to the regions of the web of material 904 passingthrough the nip 1201. As an example, see FIG. 12A, the portion 1207 ofthe felt 911 is located at the circumferential segment 1202G of the felt911, which segment 1202G may define physical circumferential segment #7,and at an axial location that is axially aligned with the pressuresensor 26A on the sensing roll 926 in the downstream nip 1201. The feltportion 1207 may be damaged such that it does not remove as muchmoisture from a region of the web of material 904 it contacts ascompared to other felt portions that remove a greater amount of moisturefrom the web of material regions they contact. Hence, because the feltportion 1207 removes less moisture content from a corresponding web ofmaterial region that it contacts, that web of material region, in turn,causes an increase in pressure in the region of the nip 1201, e.g., ofapproximately 2 psi in the illustrated example, as compared to apressure increase of about 0 psi for all other web of material regions.

Time-synchronizing the values in column 404A with the period of rotationof the felt 911 can be accomplished by associating that pressure readingvalue with one of the 37 time-based tracking segments of the period ofrotation of the felt 911 that correspond to when the pressure readingwas sensed.

As an example, the reference position 1205 on the felt 911 can make 1complete rotation around the loop pattern around the rolls 941 in thesame amount of time that the sensing roll 926 in the downstream nip 1201makes 37 rotations. Thus, the felt 911 advances by the length of one ofthe physical tracking segments (e.g., 1202A) for every rotation of thesensing roll 926. As an example and as mentioned above, the portion 1207of the felt 911 is located at the circumferential segment 1202G of thefelt 911, which segment 1202G may define the physical circumferentialsegment #7 and at an axial location that is axially aligned with thepressure sensor 26A on the sensing roll 926 in the downstream nip 1201.

Thus, a signal generator 900B generates a periodic time reference signalwhen the reference position 1205 of the felt 911 is adjacent the signalgenerator 900B. This is the reference signal from which a time-basedtracking segment of the period of rotation of the felt 911 can becalculated as the sensor 26A on sensing roll 926 passes through theregion of the nip 1201. As one example, when a pressure reading issensed and generated by the pressure sensor 26A of the sensing roll 926,the processor 903 will determine the elapsed time period in 1/37increments since the last reference signal was generated by the signalgenerator 900B. If a pressure reading was generated by the sensor 26A ofthe sensing roll 926 twenty-five ( 1/37) time increments from when thelast reference signal was generated, this would correspond to 25/37 ofthe total period of rotation of the felt 911. Thus, the pressure readingsensed at the nip 1201 can be associated with time-based trackingsegment #25. Thus, the felt rotational period can comprise m time-basedtracking segments, each having a respective, unique index value x in therange of: 1, 2, . . . , m (e.g., m=37)

In a manner similar to how data in FIGS. 4A and 4B and FIGS. 14A-14C wasarranged, or stored, in a manner time-synchronized with the rotationalperiod of the mating roll 942A and the felt 913, sensor readings fromthe region of the nip 1201 could also be arranged, or stored, in amanner time-synchronized with the period of rotation of the felt 911.

For the felt 911, the time-based tracking segment numbers (e.g.,time-based tracking segment #25) refer to logical segments of the periodof rotation of the felt 911 which have occurred from when the referencesignal was generated by the signal generator 900B until a pressurereading is sensed and generated by the pressure sensor 26A of thesensing roll 926. However, these initial time-based tracking segmentnumbers do not necessarily correspond to an identical physicalcircumferential segment on the felt 911 as measured from the referencelocation 1205. In other words, a region of the web of material in theregion of the nip 1201 concurrently with sensor 26A may arrive at the25^(th) time segment of the period of rotation of the felt 911 but thatregion of the web of material 904 was not necessarily pressed in the nipregion 1203 by the physical 25^(th) circumferential segment of the felt911 as measured from the reference location 1205. There is a delaybetween felt 911 and nip 1203 impacting the properties of the web andthe sensing of this change at a region of the nip 1201. In general,variations in the felt 911 while in the nip 1203 can impact the amountof moisture in the region of the web of material 904 concurrently in thenip 1203 and also the thickness of caliper of the web. These differencesin moisture and thickness can impact pressure values sensed at the nip1201 as the regions of the web of material 904 with different amounts ofmoisture enter a region of the nip 1201 concurrently with a sensor 26A.Thus, the variations in the felt 911 impact pressure values sensed in aregion of the nip 1201.

In addition to the time-based technique described above for identifyingdifferent tracking segments, alternative techniques are contemplated aswell. For example, the rotating felt 911 could include multiple,evenly-spaced marks that could be detected (e.g., optically) as eachsuch mark passes a sensor location. The marks would function so as toseparate the felt 911 (or 913) into different segments and a counter, orsimilar circuitry, would increment a count each time a mark was detectedso that any collected data could be associated with one of the segmentsof the felt 911. A reference mark could be distinctive from all theother marks such that when the sensor detects the reference mark, thecounter circuitry resets and starts counting from an initial value(e.g., “0” or “1”). As an example, each evenly-spaced mark could be asingle tick mark, a tick mark of a particular width, or a mark of aparticular color. The reference mark could be a double-tick mark, athicker (or thinner) tick mark, or a mark of a unique color. If thetechniques of segmenting the felt 911 just described were utilized, thenit would be unnecessary to explicitly measure an elapsed time since themost recent generation of a reference timing signal that is generatedeach revolution of the felt 911. The detectable marks can, for example,be optically detectable, magnetically detectable, detectable usinginfra-red radiation, detectable using sonic waves, detectable usingX-rays, or detectable based on radioactive emissions.

FIG. 12B provides an exemplary method for relating a time-based trackingsegment of the felt 911 to a corresponding physical circumferentialtracking segment on the felt 911. Felts, such as 911 and 913 can vary inlength, or circumference, between 50 to 300 feet for example. In anexample embodiment, the diameter of the sensing roll 926 is 2 feet whichmakes its circumference approximately 6.28 feet. Felt 911 has, in thisexample, 37 physical circumferential segments each being equivalent inlength to the circumference of the sensing roll 926. Thus, the felt 911is a little more than 232 feet in length, L_(F). The felt 911 alsorotates as a continuous band around the rolls 941 with a period ofrotation p. In a simple example, the region of the nip 1201 is locateddownstream a distance from the region of the nip 1203 that is an integermultiple of the felt length L_(F). As FIG. 12B shows, when the referencelocation 1205 is at its position to generate a new time referencesignal, there is a segment (e.g., segment #24) that is touching the webof material 904. In the illustrated embodiment, because segment #24 isthe only felt segment ever in the nip 1203 each time a new timereference signal is generated, it is designated as a “felt touchreference segment.” There are also two other regions 1260, 1262 shown onthe web of material 904 that were previously in the region of the nip1203 concurrently with the “felt touch reference segment” #24. That is,the web material region 1260 was in the region of the nip concurrentlywith the “felt touch reference segment” #24 during one prior rotation ofthe felt 911 and the web material region 1262 was in the region of thenip concurrently with the “felt touch reference segment” #24 during twoprior rotations of the felt 911.

Relative to the web of material region 1260 and subsequent to the region1260 being in the nip 1203, there is an adjacent web of material region1272 that was in the region of the nip 1203 concurrently withcircumferential segment #25 of the felt 911 and adjacent that region1272 is a web of material region 1270 that was in the region of the nip1203 with circumferential segment #26 of the felt 911. Ahead of the webof material region 1260, there is an adjacent region 1274 of the web ofmaterial that was in the region of the nip 1203 concurrently withcircumferential segment #23 of the felt 911 and a web of material region1276 was in the region of the nip 1203 concurrently with circumferentialsegment #22 of the felt 911. Each web of material region 1260, 1270,1272, 1274, 1276 has a length of 1/37^(th) of the length L_(F) of thefelt 911 corresponding to a time period ρ/37 long.

In FIG. 12B, at the sensing roll 926, the region 1262 of the web ofmaterial 904 is shown in the region of the nip 1201 with the sensor 26A.Based on the reference signal from the generator 900B, which in theillustrated embodiment is always generated concurrently with the felttouch reference segment #24 of the felt 911 being in the nip 1203, thesensed reading of the sensor 26A on the sensing roll 926 occurs during afirst time-based period tracking segment (e.g., (0≦t< 1/37*ρ)), whichfirst time-based period tracking segment starts concurrently with thegeneration of the reference signal by the generator 900B and the value“t” represents an amount of time since generation of that referencesignal. If the sensor 26A, however, was in a position to arrive in thenip 1201 during the next time-based segment of the period of rotation ofthe felt 911, x=2, then the reference location 1205 would have moved bya distance equal to one circumferential segment of the felt 911 and theweb of material 904 would have moved forward substantially the samedistance so that a region just behind region 1262 (and analogous toregion 1272) would have entered the region of the nip 1201. Accordingly,if the sensed reading occurs during the second time period trackingsegment (e.g., ( 1/37*ρ≦t< 2/47*ρ)), then the region of the web ofmaterial 904 that is in the region of the nip 1201 was also previouslyin the region of the nip 1203 concurrently with the circumferentialtracking segment #25 of the felt 911.

Accordingly, each time-based tracking segment can be easily correlatedto a physical circumferential tracking segment of the felt 911. If thereading of the sensor 26A on the sensing roll 926 takes place between

$\left( {{\frac{x - 1}{37}*\rho} \leq t < {\frac{x}{37}*\rho}} \right),$

wherein “x” is the index value of a time-based tracking segment of therotational period of the felt 911 measured from the last generatedreference signal from the generator 900B, which time-based trackingsegment occurs concurrently with the sensor 26A being in the region ofthe nip 1201, then the region of the web of material 904 in the regionof the nip 1201 was also previously in the region of the nip 1203concurrently with the physical circumferential segment of the felt 911indexed by an index value q, where q=((# of felt touch reference segment(i.e., #24 in the illustrated embodiment))+(x−1)) as measured from thereference location 1205. This index value would, of course wrap aroundto begin again at “1” when it exceeds “37”, the number of physicalcircumferential segments.

FIG. 12C illustrates a slight modification to the arrangement of FIG.12B in which the region of the nip 1201 happens to be, for examplepurposes, a distance from the region of the nip 1203 that is not aninteger multiple of the length L_(F) of the felt 911. As compared to thearrangement of FIG. 12B, the distance between the region of the nip 1201and the region of the nip 1203 in FIG. 12C has an additional span ordistance y. In the illustrated embodiment, the amount of time it takesthe web of material 904 to travel the extra distance y equals (10/37*ρ). A sensor reading from the region of the nip 1201 occurringduring the first time-based tracking segment (0≦t< 1/37*ρ) will involvea region of the web of material 904 that was also previously in theregion of the nip 1203 concurrently with the circumferential segment #14(e.g., 10 time segments before the “felt touch reference segment” (i.e.,#24 in the illustrated embodiments of FIGS. 12B and 12C) was in theregion of the nip 1203. So, more generally:

a) if the distance between the region of the nip 1201 and the region ofthe nip 1203 is greater by a span y than a multiple integer of thelength of the felt 911 (wherein the units of measure for y is in termsof physical circumferential tracking segments), and

b) if the sensor reading takes place at a time, t, wherein

$\left( {{\frac{x - 1}{37}*\rho} \leq t < {\frac{x}{37}*\rho}} \right),$

then the region of the web of material 904 in the region of the nip 1201was also previously in the region of the nip 1203 concurrently withphysical circumferential tracking segment of the felt 911 indexed by theindex value q, where q=((# of felt touch reference segment)+(x−1)−y) asmeasured from the reference location 1205. Thus, the data (e.g., sums,counts, averages) segregated into 37 time-based tracking segments can betranslated into 37 circumferential tracking segments as well.

Thus, the felt 911, or more generally a continuous band, can comprise m(e.g., m=37) physical circumferential tracking segments relative to areference location on the continuous band, each having a respective,unique index value q in the range of 1, 2, . . . , m, wherein each ofthe m time-based tracking segments can be associated with acorresponding one of m physical circumferential tracking segments. Asdescribed above, the index value x of a particular time-based trackingsegment can be calculated independently from calculating the index valueq of the corresponding circumferential tracking segment (i.e.,calculating x of a time-based tracking segment does not depend on firstdetermining q of a corresponding physical circumferential segment).

Additionally, referring back to FIG. 12B and the equation above, eachphysical circumferential tracking segment #1-#37 of the felt 911contacts the web of material 904 at an upstream location from the regionof the nip 1201; and the index value q of each physical circumferentialtracking segment #1-#37 can be calculated based on a) a distance betweenthe region of the nip 1201 and the upstream location (e.g., the nip1203), and b) the index value x of the corresponding time-based trackingsegment. More specifically, one particular circumferential trackingsegment contacts the web of material 904 at the upstream locationsubstantially concurrently with the signal generator generating thetrigger signal and can be considered a felt touch reference segment, andthe index value q of each circumferential tracking segment (e.g.,#1-#37) can be calculated based on a) a distance between the region ofthe nip 1201 and the upstream location (e.g., nip 1203), b) the indexvalue of the one particular circumferential tracking segment (e.g., #24,the felt touch reference segment), and c) the index value x of acorresponding time-based tracking segment. In each of the two scenariosfor calculating a particular physical circumferential segment indexvalue, q, based on a time-based tracking segment index value, x, justdescribed, a distance between the region of the nip 1201 and theupstream location (e.g., nip 1203) was used in the calculation. Asdescribed earlier, it may be beneficial to consider the distance betweenthe region of the nip 1201 and the upstream location (e.g., the nip1203) to be an integer multiple of the length L_(F) of the felt 911 plussome additional span or distance y, wherein the unit of measure for y isin terms of physical circumferential tracking segments.

In addition to the time-based technique described above for identifyingdifferent tracking segments, alternative techniques are contemplated aswell. FIGS. 12D, 12E and 12F illustrate an alternative wet felt station912A with a wet felt 913A traveling around four rollers 1250 in adirection shown by arrow 1270. In this alternative wet felt station912A, attributes of the felt 913A are used to determine trackingsegments. For example, the rotating felt 913A could include multiple,evenly-spaced marks that could be detected (e.g., optically) and countedas each such mark passes a location of a sensor or detector 1254. Eachtime one of the marks travels by and is detected by the sensor ordetector 1254, the detection of the mark could be considered an “event.”Thus, the detector 1254 can also include counter circuitry thatcommunicates with a processor 903B and counts or tracks the events thatoccur. The marks could also be metallic wires or threads that aredetectable with magnets or similar switches. The marks would function soas to separate the felt 913A (or the felt 911) into different segmentsand a counter, or similar circuitry, would increment a count each time amark was detected (e.g., an event) so that any collected data could beassociated with one of the segments of the felt 913A. It is alsocontemplated that the marks may not be evenly spaced.

In FIG. 12D, the felt 913A may have 37 physical circumferential segments1260A-1260AK, of which, segments 1260A, 1260X, 1260Y, 1260Z, 1260 AJ and1260AK are explicitly referenced in FIG. 12D. Separating each physicalcircumferential segment 1260 is a mark 1264 (e.g., marks 1264A, 1264X,1264Y, 1264Z, 1264AJ are explicitly shown in FIG. 12D). A reference mark1262 could be distinctive from all the other marks 1264A-1264AJ suchthat when the detector 1254 senses the reference mark 1262, the countercircuitry 1254 resets and starts counting from an initial value, or“starting count,” (e.g., “0” or “1”). Alternately, the reference markscan all be unique and specifically mark certain positions on the felt.

In the wet felt station 912A, one of the rollers 1250 forms a nip 1252with a sensing roll 926 that has a wireless device 40A for communicatingwith the processor 903B and an array of sensors 26A (e.g., 14 sensors)spaced axially along the sensing roll 926. When the sensor 26A in one ofthe axially positions on the sensing roll 926 enters a region of the nip1252 and senses a pressure reading, then that pressure value can becount synchronized with the rotation of the wet felt 913A by associatingthe sensor readings at that axial position with a current value of thecounter 1254. When the marks 1264 are spaced an equal distance apartcircumferentially, the pressure value can also be considered to be timesynchronized with the rotation of the felt 913A by associating thesensor reading at that axial position with a current value of thecounter 1254.

Each time the distinctive reference mark 1262 is detected by thedetector 1254, a starting reference signal can be generated that isassociated with each rotation of the wet felt 913A. The startingreference signal may, for example, be resetting the value of the counter1254 to a starting count such as, for example, “1”. Whenever a pressurereading is sensed by the sensor 26A in the region of the nip 1252, thenumber of tick mark counts, or the number of events, detected by thedetector/counter 1254 since that most-recent starting reference signal,or the starting count, is an indication of an amount the wet felt 913Ahas rotated around its loop pattern between when the counter 1254 wasreset and the pressure reading in the region of the nip 1252 occurred.Accordingly, each count (e.g., “1”, “2”, . . . “37”) can be associatedwith one of a plurality of count-based tracking segments wherein eachcount-based tracking segment is associated with a different physicalcircumferential segment 1260A-1260AK of the wet felt 913A in oneembodiment of the present invention. In the illustrated embodiment, eachcount-based tracking segment is equal to the count or value of thecounter. If the tick marks 1264 are evenly spaced, then the count-basedtracking segments can correspond to time-based tracking segments of theperiod of rotation of the wet felt 913A or correspond to physicalcircumferential segments of the wet felt 913A.

Similar to the techniques described above that involved timesynchronizing sensor readings for each axially-spaced sensor 26A withone of 37 possible time-based tracking segments, associating each ofthese sensor readings with one of 37 count-based tracking segments, whenthe marks 1264 are evenly spaced apart, also time synchronizes thepressure data with the rotation of the wet felt 913A.

In the example embodiment of FIG. 12D, the wet felt 913A travels alongwith the web of material 904 through the nip 1252 formed with thesensing roll 926. In such an embodiment, a particular value of thedetector/counter 1254 when a corresponding one particular physicalcircumferential segment (e.g., 1260A-1260AK) of the wet felt 913 is inthe region of the nip 1252 is associated with one of the plurality ofcount-based tracking segments. As noted above, each count-based trackingsegment corresponds to a different physical circumferential segment1260A-1260AK of the wet felt 913A. Hence, when a sensor reading isgenerated by one of the axially spaced apart sensors, the processor 903Bassociates that sensor reading with a current value of the counter 1254,associates the count generated by the counter 1254 with a correspondingcount-based tracking segment and stores that sensor reading with atracking segment corresponding to the count generated when sensorreading occurred.

FIG. 12E illustrates the felt 913A of FIG. 12D after it has rotated to adifferent position and the sensor 26A generates a sensed pressure signalof the region of the nip 1252. In particular, the felt 913A has rotatedan amount such that the tick marks 1262, 1264A, 1264B and 1264C havebeen detected and counted by the detector/counter 1254. Thus, if thecounting of the tick marks starts with “1” as the distinctive tick mark1262 is detected, an example count for the position of the felt 913A ofFIG. 12E would be “4” when the sensor reading from sensor 26A iscaptured. This count value would correspond to one of the 37 (forexample) tracking segments that each of the sensor readings will beassociated with and each such tracking segment (or count value) wouldcorrespond to a different physical circumferential segment 1260A-1260AKof the wet felt 913A. As shown in FIG. 12E, corresponding to this countvalue of “4”, the physical circumferential segment 1260F of the felt913A is in the region of the nip 1252. Accordingly, a plurality ofsensed pressure readings from the region of the nip 1252 associated withthe tracking segment, or count reading, of “4” could all be associatedwith the physical circumferential segment 1260F of the felt 913A.Continuing with the example of FIG. 12E, when the felt rotates such thatthe tick mark 1264D is detected and counted, the tracking segment, orcount value, will be “5” and will correspond to pressure readings sensedwhen physical circumferential segment 1260G is in the region of the nip1252.

The embodiment of FIG. 12A could be modified as well such that the felt911 includes tick marks and the wet felt station 910 includes acounter/detector instead of the time-based-signal generator 900B. Thepressure readings sensed in the region of the nip 1201 could by countsynchronized with the rotation of the wet felt 911 based on a countvalue rather than an elapsed time. Thus, the count-based trackingsegment determination and count synchronization described with respectto FIG. 12D could be applied to either a felt that travels through a nipwhere pressure values are sensed or a felt that is upstream from the nipwhere the pressure values are being sensed.

FIG. 12F depicts a portion of the wet felt 913A that is traveling aroundin a loop pattern in a direction shown by the arrow 1270. The portion ofthe felt 913A in FIG. 12F shows a distinctive reference mark 1262 andfour other nearby marks 1264A, 1264B, 1264AJ and 1274AI that are evenlyspace relative to circumferential segments 1260A, 1260B, 1260AJ, and1260AK of the wet felt 913A. As an example, each evenly-spaced markcould be a single tick mark (e.g., 1264A, 1264B, 1264AI and 1274AJ), atick mark of a particular width, or a mark of a particular color. Thedistinctive reference mark 1262 could be a double-tick mark, a thicker(or thinner) tick mark, or a mark of a unique color. Such tick marks canalso be used to encode positional information (such as the numbers 1 to37) associated with each segment. If the techniques of segmenting thefelt 913A (or 911) just described were utilized, then it would beunnecessary to explicitly measure an elapsed time since the most recentgeneration of a reference timing signal that is generated eachrevolution of the felt 913A; instead, detection and counting of tickmarks (e.g., 1264A-1264AJ) since the distinctive reference mark 1262could be used to define a plurality of count-based tracking segments.

The position of the marks, 1262, 1264A, 1264B, 1264AJ, and 1264AK inFIG. 12F is provided merely by way of example. They can extend along theentire axial width of the felt 913A, be localized next to one or bothedges of the felt 913A, or be located in the middle of the felt 913A.They are located such that they can be detected by the detector/counter1254 as the felt 913A travels past a location proximate to thedetector/counter 1254.

One of ordinary skill in this technological field will recognize thatidentifiable tick marks or other types of markings can be provided in avariety of different ways without departing from the scope of thepresent invention. For example, each mark may be encoded such that eachis uniquely identifiable. An appropriate sensor would, therefore, notnecessarily “count” the tick marks but merely identify which tick markis presently passing by the sensor. Thus, each tick mark could beassociated with or define a value, possibly a unique value, that can besensed between when a most recent starting reference was generated andwhen a sensor (e.g., 26A) enters a region of a nip where a pressurereading, or other reading, is being sensed. Accordingly, one of aplurality of tracking segments associated with the continuous band canbe identified based on this value.

In addition to being on a surface of one of the felts, the tick marks,or similar marks or openings, could be included on a disk coupled to arotating shaft or on the shaft itself associated with one of themultiple rotating components that help drive the felt around itscontinuous loop. Such an arrangement may be used to provide a rotaryencoder beneficial in identifying respective tracking segments of a feltor other continuous band. As one example, a shaft encoder of this typecould provide a value that corresponds to a count of the number of tickmarks or openings that were detected between when a most recent startingreference was generated and when a sensor (e.g., 26A) enters a region ofa nip where a pressure reading, or other reading, is being sensed.Accordingly, one of a plurality of tracking segments associated with thecontinuous band can be identified based on this value.

In addition to the above examples, each respective tracking segment of acontinuous band, which could be either time-based segments of a periodof rotation of the band or physical circumferential segments of theband, can also correspond to a value that occurs between when a mostrecent starting reference was generated and when a sensor (e.g., 26A)enters a region of a nip where a pressure reading, or other reading, isbeing sensed. Each such tracking segment could correspond to a differentvalue such as, for example, an index number of the tracking segment asmeasured from a reference such as a time-based reference signal or areference location or position of the band.

Returning to the felt 911 of FIG. 12A, the felt 911 can be segmentedinto cross-machine direction (or axial) segments similar to the felt 913being segmented into axial segments corresponding to the differentlocations of the sensors 26A on the sensing roll 926. Thus, the felt 911can be broken into multiple axial segments that each correspond to oneof the sensor locations on the sensing roll 926 and data similar to thatof FIGS. 14A-14C can be collected for each axial segment. Accordingly,similar matrices of “counts”, “sums” and “averages” as described inFIGS. 6-8 can be constructed for the data similar to FIGS. 14A-14C foreach axial segment but arranged in a manner time-synchronized with theperiod of rotation of the felt 911. In the example provided above, eachsuch matrix would have (37×14), or 518, cells because the felt 911, ormore generally a continuous band, comprises n axial segments, havingrespective index values: 1, 2, . . . , n (e.g., n=14) and the feltrotational period comprises m time-based tracking segments, each havinga respective, unique index value x in the range of: 1, 2, . . . , m(e.g., m=37) which creates (n times m) unique permutations that areidentifiable by a two-element set comprising a respective axial segmentindex value and a respective time-based tracking segment index value.So, as mentioned above, for a plurality of respective sensor signals andfor one or more of the possible (n times m) permutations, each cell of amatrix can be calculated that represents an average of all the pluralityof respective sensor signals associated with an axial segment andtime-based tracking segment matching each of the one or morepermutations.

The pressure readings in column 404A of FIGS. 14A-14C involve less thanonly 100 different sensor readings from one sensor 26A. However, if datafrom over 1000, 2000 or even 5000 sensor readings from each of thesensors in a sensing roll is collected, then the time-synchronization ofdata can reveal effects that different stations, e.g., wet felt stations908, 910 and 912, in the process/system line of FIG. 9 can have on thosepressure readings. The values in column 404A correspond to differentsequential sensor readings as numbered in column 402A. However,depending on how those pressure reading values are associated withperiodically repeating tracking segments, patterns in the pressurereadings may become apparent.

As shown by element 1412 in column 406A, there can be 22 mating rolltracking segments such that each pressure reading (from column 404A) isassociated with one of those tracking segments. As described earlierwith respect to the matrices of FIGS. 6-8, each sensor reading in column404A can be associated with only one axial position (or sensor positionof the one sensor generating those pressure readings) and any one of anumber of tracking segments (e.g., 1-22) of a monitored component in theprocess/system of FIG. 9. In the following discussion, an assumption ismade that the example axial segment is “Axial Segment #1”. Everypressure reading in column 404A that is associated with mating rolltracking segment 1 is added together. The number of those segments canthen be divided into the sum to arrive at an average pressure readingfor tracking segment 1. A similar average can be calculated for each ofthe 21 other mating roll tracking segments as well. Similar averages canbe calculated for all of the 21 mating roll tracking segmentscorresponding to the remaining axial segments, i.e., Axial Segment #2through Axial Segment #14. Thus, an average pressure matrix, such as theone described with respect to FIG. 8, can be constructed for the matingroll 942A.

FIG. 15A illustrates an average pressure matrix for the mating roll 942Aconstructed by extending the simulation data of FIGS. 14A-14C to 5,000pressure readings. Column 1502 represents the tracking segments of themating roll 942A with each row representing one of those 22 trackingsegments. Each column 1506 represents one of the axial positions of thesensors 26 (for example, 14 axial positions). The extended pressurereading data in column 404A of FIGS. 14A-14C represents one particularaxial position such as “Axial Segment 1” and, thus, is used to calculatethe value in a single column 1506A of the matrix of FIG. 15A. A value1508 in row 5 of the matrix is an average of all the pressure readingsof column 404A that are associated with tracking segment 5 of the matingroll 942A.

FIG. 15B illustrates an average pressure matrix for the felt 913constructed by extending the simulation data of FIGS. 14A-14C to 5,000pressure readings. Column 1512 represents the tracking segments of thefelt 913 with each row representing one of those 31 tracking segments.Each column 1516 represents one of the axial positions of the sensors26. The extended pressure reading data in column 404A of FIGS. 14A-14Crepresents one particular axial position such as “Axial Segment 1” and,thus, is used to calculate the value in a single column 1516A of thematrix of FIG. 15B. A value 1518 in row 27 of the matrix is an averageof all the pressure reading of column 404A that are associated withtracking segment 27 of the felt 913. In particular, the average value inrow 27 is significantly higher than the values in the other rows ofcolumn 1516 and could represent a defect of the felt 913 such as aplugged spot that is periodically causing lower water removal.

FIG. 15C illustrates an average pressure matrix for the felt 911constructed by extending the simulation data of FIGS. 14A-14C to 5,000pressure readings. Column 1522 represents the time-based trackingsegments of the felt 911 with each row representing one of those 37tracking segments. Each column 1526 represents one of the axialpositions of the sensors 26. The extended pressure reading data incolumn 404A of FIGS. 14A-14C represents one particular axial positionsuch as “Axial Segment 1” and, thus, is used to calculate the value in asingle column 1526A of the matrix of FIG. 15C. A value 1528 in row 25 ofthe matrix is an average of all the pressure reading of column 404A thatare associated with time-based tracking segment 25 of the felt 911. Thetime-based tracking segment 25 does not necessarily correspond tophysical circumferential tracking segment 25 of the felt 911 being inthe nip 1203 concurrently. However, as described above, the physicalcircumferential segment of the felt 911 in the nip 1203 corresponding tothe time-based tracking segment 25 can be calculated. In particular, theaverage value in row 25 is approximately 2 psi higher than many of thevalues in the other rows and could represent a defect in the felt 911,such as a region of the felt that is plugged or a thin spot of the felt911 that does not remove water as readily as surrounding areas of thefelt 911, that is periodically affecting the web of material 904.

FIG. 16 illustrates graphically the different time-synchronizedarrangements of the same sensor data readings in accordance with theprinciples of the present invention. In particular the waveforms of FIG.16 represent the 5000 sensor readings taken by a single sensor 26A onthe sensing roll 926 used to construct columns 1506A, 1516A and 1526A ofthe matrices of FIG. 15A-15C.

The waveform 1602 has the mating roll tracking segment index as itsx-value and the corresponding average pressure reading from column 1506Aof the matrix of FIG. 15A for that segment index as the y-value. Thewaveform 1604 has the felt tracking segment index of the felt 913 as itsx-value and the corresponding average pressure reading from column 1516Aof the matrix of FIG. 15B for that segment index as the y-value. Thewaveform 1608 has the felt 911 time-based tracking segment index as itsx-value and the corresponding average pressure reading from column 1526Aof the matrix of FIG. 15C for that segment index as the y-value. Thepeaks of the waveforms 1604 and 1608 correspond to the values 1518 and1528 from FIG. 15B and FIG. 15C.

As mentioned above, the average pressure matrices, or theircorresponding waveforms, can be analyzed to identify potential issueswith one or more stations in the process/system of FIG. 9. The waveform1602 reveals a sinusoidally changing pressure value based on whichtracking segment of the mating roll 942A is traveling through the regionof the nip 1201 at an axial location corresponding to pressure sensor26A, which sensor 26A corresponds to Axial Segment 1. This, for example,could be caused by the mating roll 942A having an oval cross-sectionalshape at that axial position, rather than a circular cross-section. Thewaveform 1604 reveals a significant pressure pulse associated withtracking segment #27 of the felt 913 at an axial location correspondingto pressure sensor 26A as compared to the other 30 tracking segments ofthe felt 913 at that axial location. The waveform 1608 reveals anidentifiable pressure pulse associated with time-based tracking segment#25 of the period of rotation of the felt 911 at an axial locationcorresponding to pressure sensor 26A as compared to the 36 othertracking segments of the felt 911 at that same axial location.

In FIG. 13, the sensing roll 918 is associated with a region of a nip212A of the pressing region 916 of the felt station 908 that, in thisexample, is closest to the wire mesh 906. However, pressure values canbe sensed at other, further downstream stations as well withoutdeparting from the scope of the present invention. Similar to the felts911 and 913, the wire mesh 906 rotates as a continuous band in a looppattern around rolls 1302 and 1304. Accordingly, the wire mesh 906 has aregular period of rotation around this loop pattern. Thus, differentportions of the wire mesh 906 each periodically contact correspondingregions of the web of material 904 upstream from the region of the nip212A even though the wire mesh 906 itself does not travel through theregion of the nip 212A. The region of the nip 212A is formed between thesensing roll 918 and a mating roll 940A in the wet felt station 908. Thesensing roll 918 includes a wireless transmitter 40B (substantiallysimilar to the wireless devices 40, 40A described above) and a sensorarray having a plurality of axially spaced apart sensors 1302(substantially similar to each sensor 26 described above), with only asingle sensor 1302A at one corresponding axial location illustrated inFIG. 13. In a similar manner to that described with respect to FIG. 5, aprocessor 903A receives signals from a signal generator 900C and thewireless device 40B in order to time synchronize sensor readings fromthe sensing roll 918 with the periodic time reference signal from thesignal generator 900C. In the example embodiment of FIG. 13, a simple,single wire mesh 906 is described; however, other elements may beassociated with the wire mesh 906 such as a top wire and/or a verticalformer. One of ordinary skill will recognize that a variety of otherelements can be associated with the wire mesh 906 of FIG. 13 such asadditional rolls that contact an inner surface of the mesh 906 to carrythe mesh 906 evenly and prevent it from sagging and vacuum boxes andfoils (not shown) can be provided to pull moisture from the slurrythrough the mesh 906.

In FIG. 13, a portion 1309 of the wire mesh 906, having a correspondingaxial and circumferential location, is shown that contacts the web ofmaterial 904 in a periodic manner as the web of material 904 is carriedby the wire mesh 906. Identified web of material regions 1310 and 1312are evenly spaced and were in contact with the portion 1309 of the wiremesh 906. When one of those web of material regions travels through theregion of the nip 212A, the pressure reading from the sensing roll 918can be affected by the impact that the wire mesh portion 1309 had on theweb of material 904 that it contacted. Similar to the explanationrelating to felts, the condition of the wire mesh 906 that contacts theweb of material 904 can affect, for example, the amount of moisture thatis able to drain from the contacted region of the web of material 904.Thus, some regions of the web of material 904 may be wetter or drierrelative to one another and cause higher or lower pressure readings whenpassing through the region of the nip 212A. Changes to the web ofmaterial 904 are caused by gravity, vacuum and foils and vacuum pullingwater from the slurry through the wire mesh 906. Both water weight(moisture) and dry weight of the slurry can be impacted. Plugs in thewire mesh 906 may cause solids of the slurry to shift position. Holes ofworn areas in the wire mesh 906 may cause solids in the slurry to belost and pass through the mesh 906 and result in a light weight region.

The wire mesh 906 can have a period of rotation that can be broken intodifferent time-based tracking segments in the same manner as the periodof rotation of the felt 911 was broken into 37 time-based trackingsegments as described earlier which each could also be translated into acorresponding one physical circumferential tracking segment of the felt911. Thus, the tracking segments related to the wire mesh 906 can eitherbe a plurality of time-based segments of the period of rotation of thecontinuous band around the loop pattern or a plurality of physicalcircumferential segments on the continuous band. Segments 1307, as shownin FIG. 13, may, for example, be separate physical circumferentialsegments with each having an index relative to a fixed referenceposition 1308 on the wire mesh 906.

As an example, the reference position 1308 can make 1 complete rotationaround the loop pattern in the same amount of time that the sensing roll918 makes 43 rotations. For example, if the sensing roll 918 is about 6feet in circumference, then in this example, the circumference of thewire mesh 906 would be about 258 feet (e.g., 6*43). Using the sameprinciples as used when describing the felt 911 of FIG. 12A, the mesh906 can be segmented into 43 tracking segments, for example. As anexample, the portion 1309 of the wire mesh 906 that, for example, has acircumferential tracking segment and an axial location, may cause apressure pulse in the region of the nip 212A as compared to all otherportions of the wire mesh 906 if it is plugged or a pressure dip in theregion of the nip 212A as compared to all other portions of the wiremesh 906 if it has a hole worn in it.

Thus, a signal generator 900C generates a periodic time reference signalwhen a reference position 1308 of the wire mesh 906 is adjacent thesignal generator 900C. This is the reference signal from which atime-based tracking segment can be calculated as the sensor 1302A passesthrough the region of the nip 212A. As one example, when any of the webof material regions 1310 or 1312 passes through the nip 212A and issensed, the processor 903A can determine the elapsed time period sincethe last reference signal was generated in a manner similar to thatdescribed above with respect to felt 911 in FIGS. 12B and 12C. Thus, thepressure readings sensed at those times can all be associated with thesame time-based tracking segment of the period of rotation of the mesh906. The portion 1309 of the wire mesh 906 that corresponds to thistime-based tracking segment can be calculated in a manner similar tothat described above with respect to felt 911 in FIGS. 12B and 12C.Thus, the pressure readings from the region of the nip 212A that areassociated with different time-based tracking segments can also beassociated with corresponding circumferential tracking segments of themesh 906 relative to the reference position 1308.

In a manner similar to how data in FIGS. 4A and 4B, FIGS. 14A-14C andFIG. 15A-15C was collected in a manner time-synchronized with therotational period of the mating roll 11, the felt 913, and the felt 911,sensor readings from the region of the nip 212A could also be collectedin a manner time-synchronized with the period of rotation of the wiremesh 906. Also, similar to the tick marks and count-based trackingsegments described in FIG. 12D and FIG. 12E with respect to the felt913A, a similar count-based technique can be utilized with respect tothe wire mesh 906 in order to collect sensor data in a mannertime-synchronized with the rotation of the wire mesh 906.

FIG. 17 is a flowchart of an exemplary method of time-synchronizing datain accordance with the principles of the present invention. Inparticular, the method can be associated with a sensing roll andpossibly upstream felts and wires. The method begins in step 1702 bygenerating a respective sensor signal from each of a plurality ofsensors located at axially spaced-apart locations of the sensing roll.More particularly, each respective sensor signal is generated when eachsensor enters a region of a nip between the sensing roll and the matingroll during each rotation of the sensing roll. This is because thesensing roll and mating roll are located relative to one another tocreate the nip therebetween and there is also a web of material thattravels through the nip from an upstream direction to a downstreamdirection. Furthermore there is a continuous band arranged to travelaround in a loop pattern that contacts at least a region of the web ofmaterial at the nip or upstream from the nip. The method continues instep 1704 by generating a periodically occurring time referenceassociated with each rotation of the continuous band around the looppattern. Next, in accordance with the method, the respective sensorsignal generated by each sensor is received in step 1706. In step 1708,upon receiving the respective sensor signal, the method involves threedifferent actions: a) determining a particular one of the plurality ofsensors which generated the respective sensor signal, b) identifying oneof a plurality of tracking segments associated with the continuous bandbased upon an amount of time that elapsed between when the respectivesensor signal was generated and a most recent time reference, and c)storing the respective sensor signal to associate the respective sensorsignal with the identified one tracking segment. Of particular note,each of the plurality of tracking segments is, respectively, associatedwith a different amount of elapsed time. In accordance with the methodof FIG. 17, the continuous band can comprise either a press felt or awire mesh. Furthermore, the continuous band may pass through the nip ormerely contact a region of the web of material upstream from the nip.

While particular embodiments of the present invention have beenillustrated and described, it would be obvious to those skilled in theart that various other changes and modifications can be made withoutdeparting from the spirit and scope of the invention. It is thereforeintended to cover in the appended claims all such changes andmodifications that are within the scope of this invention.

1. A system associated with a sensing roll and a mating roll forcollecting roll data comprising: the sensing roll and mating rolllocated relative to one another to create a nip therebetween, wherein aweb of material travels through the nip from an upstream direction to adownstream direction and a continuous band, arranged to travel around ina loop pattern, contacts at least a region of the web of materialupstream from the nip; a plurality of sensors located at axiallyspaced-apart locations of the sensing roll, wherein each sensor enters aregion of the nip during each rotation of the sensing roll to generate arespective sensor signal; structure for generating a periodicallyoccurring time reference associated with each rotation of the continuousband around the loop pattern; and a processor to receive theperiodically occurring time reference and the respective sensor signalgenerated by each sensor and, after receiving the respective sensorsignal, the processor operates to: determine a particular one of theplurality of sensors which generated the respective sensor signal, basedupon an amount of time that elapsed between when the respective sensorsignal was generated and a most recent time reference, identify one of aplurality of time-based tracking segments associated with the continuousband, wherein each of the plurality of tracking segments is,respectively, associated with a different amount of elapsed time, andstore the respective sensor signal to associate the respective sensorsignal with the identified one time-based tracking segment.
 2. Thesystem of claim 1, wherein the continuous band comprises a press felt.3. The system of claim 1, wherein the continuous band comprises a wiremesh.
 4. The system of claim 1, wherein the continuous band does nottravel through the nip.
 5. The system of claim 1, wherein the receivedsensor signal comprises a pressure value.
 6. The system of claim 1,wherein the processor receives: the respective sensor signal for each ofthe plurality of sensors during each rotation of the sensing roll, and aplurality of the respective sensor signals occurring during a pluralityof rotations of the sensing roll.
 7. The system of claim 6, wherein, foreach one of the plurality of the respective sensor signals, theprocessor identifies an associated continuous band axial segment and itsidentified one time-based tracking segment.
 8. The system of claim 7,wherein: the continuous band comprises n axial segments, havingrespective index values: 1, 2, . . . , n; a continuous band rotationalperiod comprises m time-based tracking segments, each having arespective, unique index value x in the range of: 1, 2, . . . , m, andwherein there are (n times m) unique permutations that are identifiableby a two-element set comprising a respective axial segment index valueand a respective time-based tracking segment index value.
 9. The systemof claim 8, wherein, for the plurality of respective sensor signals andfor one or more of the possible (n times m) permutations, the processordetermines an average of all the plurality of respective sensor signalsassociated with an axial segment and time-based tracking segmentmatching each of the one or more permutations.
 10. The system of claim8, wherein the continuous band comprises: m circumferential trackingsegments relative to a reference location on the continuous band, eachhaving a respective, unique index value q in the range of: 1, 2, . . . ,m, and, wherein each time-based tracking segment is associated with acorresponding circumferential tracking segment.
 11. The system of claim10, wherein the index value x of a particular time-based trackingsegment is calculated independently from calculating the index value qof the corresponding circumferential tracking segment.
 12. The system ofclaim 10, wherein: each circumferential tracking segment of thecontinuous band contacts the web of material at an upstream locationfrom the region of the nip; and the index value q of eachcircumferential tracking segment is calculated based on a) a distancebetween the region of the nip and the upstream location and b) the indexvalue x of the corresponding time-based tracking segment.
 13. The systemof claim 10, wherein the structure for generating a periodicallyoccurring time reference comprises: a signal generator to generate atrigger signal on each rotation of the continuous band as the referencelocation on the continuous band travels past a predetermined position.14. The system of claim 13, wherein: each circumferential trackingsegment of the continuous band contacts the web of material at anupstream location from the region of the nip; one particularcircumferential tracking segment contacts the web of material at theupstream location substantially concurrently with the signal generatorgenerating the trigger signal, and the index value q of eachcircumferential tracking segment is calculated based on a) a distancebetween the region of the nip and the upstream location, b) the indexvalue of the one particular circumferential tracking segment, and c) theindex value x of the corresponding time-based tracking segment.
 15. Amethod associated with a sensing roll and a mating roll for collectingroll data comprising: generating a respective sensor signal from each ofa plurality of sensors located at axially spaced-apart locations of thesensing roll, wherein each respective sensor signal is generated wheneach sensor enters a region of a nip between the sensing roll and themating roll during each rotation of the sensing roll; the sensing rolland mating roll located relative to one another to create the niptherebetween, wherein a web of material travels through the nip from anupstream direction to a downstream direction and a continuous band,arranged to travel around in a loop pattern, contacts at least a regionof the web of material upstream from the nip; generating a periodicallyoccurring time reference associated with each rotation of the continuousband around the loop pattern; and receiving the respective sensor signalgenerated by each sensor and, after receiving the respective sensorsignal: determining a particular one of the plurality of sensors whichgenerated the respective sensor signal, based upon an amount of timethat elapsed between when the respective sensor signal was generated anda most recent time reference, identifying one of a plurality oftime-based tracking segments associated with the continuous band,wherein each of the plurality of time-based tracking segments is,respectively, associated with a different amount of elapsed time, andstoring the respective sensor signal to associate the respective sensorsignal with the identified one time-based tracking segment.
 16. Themethod of claim 15, wherein the continuous band comprises a press felt.17. The method of claim 15, wherein the continuous band comprises a wiremesh.
 18. The method of claim 15, wherein the continuous band does nottravel through the nip.
 19. The method of claim 15, wherein the receivedsensor signal comprises a pressure value.
 20. The method of claim 15,comprising: receiving the respective sensor signal for each of theplurality of sensors during each rotation of the sensing roll, andreceiving a plurality of the respective sensor signals occurring duringa plurality of rotations of the sensing roll.
 21. The method of claim20, comprising: for each one of the plurality of the respective sensorsignals, identifying an associated continuous band axial segment and itsidentified one time-based tracking segment.
 22. The method of claim 21,wherein: the continuous band comprises n axial segments, havingrespective index values: 1, 2, . . . , n; a continuous band rotationalperiod comprises m time-based tracking segments, each having arespective, unique index value x in the range of: 1, 2, . . . , m, andwherein there are (n times m) unique permutations that are identifiableby a two-element set comprising a respective axial segment index valueand a respective time-based tracking segment index value.
 23. The methodof claim 22, comprising: for the plurality of respective sensor signalsand for one or more of the possible (n times m) permutations,determining an average of all the plurality of respective sensor signalsassociated with an axial segment and time-based tracking segmentmatching each of the one or more permutations.
 24. The method of claim22, wherein the continuous band comprises: m circumferential trackingsegments relative to a reference location on the continuous band, eachhaving a respective, unique index value q in the range of: 1, 2, . . . ,m, and, wherein each time-based tracking segment is associated with acorresponding circumferential tracking segment.
 25. The method of claim24, wherein the index value x of a particular time-based trackingsegment is calculated independently from calculating the index value qof the corresponding circumferential tracking segment.
 26. The method ofclaim 24, wherein: each circumferential tracking segment of thecontinuous band contacts the web of material at an upstream locationfrom the region of the nip; and the index value q of eachcircumferential tracking segment is calculated based on a) a distancebetween the region of the nip and the upstream location and b) the indexvalue x of the corresponding time-based tracking segment.
 27. The methodof claim 24, wherein generating a periodically occurring time referencecomprises: generating a trigger signal on each rotation of thecontinuous band as the reference location on the continuous band travelspast a predetermined position.
 28. The method of claim 27, wherein: eachcircumferential tracking segment of the continuous band contacts the webof material at an upstream location from the region of the nip; oneparticular circumferential tracking segment contacts the web of materialat the upstream location substantially concurrently with the signalgenerator generating the trigger signal, and the index value q of eachcircumferential tracking segment is calculated based on a) a distancebetween the region of the nip and the upstream location, b) the indexvalue of the one particular circumferential tracking segment, and c) theindex value x of the corresponding time-based tracking segment.